The bizarre flashing lights on a smartwatch

Summary by Krater

Steve Mould and his friend Andrew try to replicate the pulse and heart rate monitoring of smartwatches and pulse oximeters using just a camera and computer software, explaining how RGB and infrared light interact with blood oxygenation.

From the video

Answers: Can you measure heart rate and blood oxygen with a normal camera?

• motion amplification
• photoplethysmography
• heart rate monitoring from video
• pulse oximetry
• RGB color channels in video processing
• infrared light blood oxygen detection

What it concludes

• Smartwatches and pulse oximeters use red and green light sensors to measure pulse and blood oxygen levels by detecting how light is reflected through blood.
• Green LED signals are stronger in red, green, and blue channels because green light penetrates deeper into the skin to reach blood vessels.
• Infrared light becomes less intense the more oxygenated your blood is, which is the opposite behavior of visible red light.
• Combining red and infrared light readings allows accurate blood oxygen measurement regardless of ambient light variations and vein depth.