The Apple Watch does not play nicely with some tattoos

Re:The Apple Watch does not play nicely with some tattoos by conphill on Wednesday April 29, 2015 @09:46AM (#9458189)

So I have a basic understanding that blood is red due to the chemical bond between iron and oxygen, and how both elements together reflect light, but out of curiosity, can anyone touch on the significance of green light?

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Re:The Apple Watch does not play nicely with some tattoos by draven on Wednesday April 29, 2015 @10:02AM (#9458281)

The section "The science behind Apple's sensors" in the article contains some details about that.

Quick google search returned this: https://en.wikipedia.org/wiki/Photoplethysmogram

According to this: http://bsn2014.org/poster/BSN2014-poster09s-maeda.pdf Green light seems to be used to lessen the impact of motion on the measurements.

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Re:The Apple Watch does not play nicely with some tattoos by conphill on Wednesday April 29, 2015 @10:41AM (#9458579)

Awesome resources. Thanks for providing this.

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Re:The Apple Watch does not play nicely with some tattoos by conphill on Wednesday April 29, 2015 @10:40AM (#9458566)

Interesting. Thanks for the short and sweet answer.

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Re:The Apple Watch does not play nicely with some tattoos by detaro on Wednesday April 29, 2015 @10:06AM (#9458304)

Green light absorbed by the red blood, heartbeats change how much blood is below the sensor -> be measuring how much light is (not) reflected it can work out the pulse. (it also has a mode using infrared light, but that is used only in special cases)

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