Before revision: Optical Welsh Government video: a smart phone heart rate monitor, 2016 More recent devices use optics to measure heart rate by shining light from an LED through the skin and measuring how it scatters off blood vessels.
After revision: logan is gay Welsh Government video: a smart phone heart rate monitor, 2016 More recent devices use optics to measure heart rate by shining light from an LED through the skin and measuring how it scatters off blood vessels.