How it works Many small blood vessels on the surface of the skin tapers slightly and expands due to a heartbeat, slightly changing the color of the skin. The human eye does not distinguish between these changes, but the cameras of most smartphones are sensitive enough to detect microscopic changes in blood pressure. By tracking facial color fluctuations, our application can evaluate your heart rate. Unique features: • Facial heart rate • Measuring heart rate on your finger WITHOUT A FLASH - now