Physics describes how oxygen saturated blood looks in the infrared, but using that information in a device is engineering. The engineers who design these device

Physics describes how oxygen saturated blood looks in the infrared, but using that information in a device is engineering. The engineers who design these devices should have better understood how something obvious like skin color would bias the measurements. It seems like the physics could be exploited again via a visible light sensor that detects darker skin. This is absolutely bias, and it is entirely due to engineering choices made by people, not nature.