Wearable devices like smartwatches and fitness trackers have revolutionized the way we monitor our health. Worn around the clock, these devices quietly collect valuable data—from heart rate and blood oxygen levels to sleep quality—giving users a real-time window into their well-being without disrupting their daily lives.

This technology, supported by deep learning, captures an eight-second video using the front camera every time a user unlocks their phone. The video information is then used to passively monitor heart rate from a distance by detecting subtle changes in skin color caused by blood flow. To ensure participants’ privacy was not compromised, videos remained on their devices until they were manually reviewed and approved for upload.