O2 Reading

[Andersama]

If I'm not entirely mistaken, PPG sensors are capable of gauging O2 levels. The project appears to use a PPG sensor to determine heart rate, but not O2. I'm not sure if that's in part because there's some variation in these sensors, if that's the case. I'd suggest considering making both a future upgrade. If it's strictly software related, my understanding is it should be proportional / related to the light sensor's reading.

[vkareh]

To detect O2 levels (SpO₂) you need two lights:

• 940nm (infrared) for oxygenated hemoglobin
• 660nm (red) for deoxygenated hemoglobin

Both are needed, since oxygen levels are a ratio between them.

The sensor in the PineTime is an HRS3300, which uses a 525nm green light.

Sources:

• https://en.wikipedia.org/wiki/Pulse_oximetry#Mode_of_operation
• https://files.pine64.org/doc/datasheet/pinetime/HRS3300%20Heart%20Rate%20Sensor.pdf

[Andersama]

Cool that'd be a future hardware upgrade to consider then.