Core's biosensors (the metal dots on the top white half of Core) use an electrocardiogram (ECG) in order to measure your body's response to a meditation or breathing technique. An ECG is a measure of the electrical activity of your heart: with each heartbeat, an electrical impulse (or wave) travels through your heart, causing the muscle to squeeze and pump blood. The metal sensors on top of Core allow us to detect that electrical wave through your thumbs, measuring exactly when your heart is beating over the course of a session.
We use this data to generate a graph of your heart rate and to calculate your heart rate variability. These metrics provide a window into how your nervous system is responding to your experience on a given day.