Your phone can use tiny skin-colour changes to measure your heart rate

Researchers developed a method to measure heart rate using subtle changes in skin color detected by a smartphone's camera on June 3, 2026. This non-invasive technique analyzes the light reflected from the fingertip when it's placed over the camera and flash, identifying the pulsatile blood flow. The system achieved an average error of 3.7 beats per minute (bpm) in tests involving 14 participants, with a maximum error of 11.4 bpm. This passive monitoring approach could enable continuous heart rate tracking during everyday phone usage, potentially alerting users to health anomalies. The study, published in Nature, also explored Richard Feynman's solution to the "restaurant dilemma" problem, which involves determining how to split a bill fairly when individuals have consumed different amounts. The heart rate monitoring method leverages photoplethysmography (PPG), a technique commonly used in wearable devices, but adapted for standard smartphone hardware. The algorithm processes video frames to isolate the subtle color variations caused by blood volume changes in the capillaries under the skin. This innovation could lead to more accessible and integrated health monitoring solutions without requiring dedicated wearable devices. The accuracy achieved suggests potential for clinical applications, though further validation in diverse populations and conditions would be necessary.